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  <div class="section" id="s-module-django.contrib.formtools.preview">
<span id="s-form-preview"></span><span id="module-django.contrib.formtools.preview"></span><span id="form-preview"></span><h1>Form preview<a class="headerlink" href="#module-django.contrib.formtools.preview" title="Permalink to this headline">¶</a></h1>
<p>Django comes with an optional &#8220;form preview&#8221; application that helps automate
the following workflow:</p>
<p>&#8220;Display an HTML form, force a preview, then do something with the submission.&#8221;</p>
<p>To force a preview of a form submission, all you have to do is write a short
Python class.</p>
<div class="section" id="s-overview">
<span id="overview"></span><h2>Overview<a class="headerlink" href="#overview" title="Permalink to this headline">¶</a></h2>
<p>Given a <a class="reference internal" href="../../forms/api.html#django.forms.Form" title="django.forms.Form"><tt class="xref py py-class docutils literal"><span class="pre">django.forms.Form</span></tt></a> subclass that you define, this
application takes care of the following workflow:</p>
<ol class="arabic simple">
<li>Displays the form as HTML on a Web page.</li>
<li>Validates the form data when it&#8217;s submitted via POST.
a. If it&#8217;s valid, displays a preview page.
b. If it&#8217;s not valid, redisplays the form with error messages.</li>
<li>When the &#8220;confirmation&#8221; form is submitted from the preview page, calls
a hook that you define &#8211; a <tt class="docutils literal"><span class="pre">done()</span></tt> method that gets passed the valid
data.</li>
</ol>
<p>The framework enforces the required preview by passing a shared-secret hash to
the preview page via hidden form fields. If somebody tweaks the form parameters
on the preview page, the form submission will fail the hash-comparison test.</p>
</div>
<div class="section" id="s-how-to-use-formpreview">
<span id="how-to-use-formpreview"></span><h2>How to use <tt class="docutils literal"><span class="pre">FormPreview</span></tt><a class="headerlink" href="#how-to-use-formpreview" title="Permalink to this headline">¶</a></h2>
<ol class="arabic">
<li><p class="first">Point Django at the default FormPreview templates. There are two ways to
do this:</p>
<ul class="simple">
<li>Add <tt class="docutils literal"><span class="pre">'django.contrib.formtools'</span></tt> to your
<a class="reference internal" href="../../settings.html#std:setting-INSTALLED_APPS"><tt class="xref std std-setting docutils literal"><span class="pre">INSTALLED_APPS</span></tt></a> setting. This will work if your
<a class="reference internal" href="../../settings.html#std:setting-TEMPLATE_LOADERS"><tt class="xref std std-setting docutils literal"><span class="pre">TEMPLATE_LOADERS</span></tt></a> setting includes the
<tt class="docutils literal"><span class="pre">app_directories</span></tt> template loader (which is the case by
default). See the <a class="reference internal" href="../../templates/api.html#template-loaders"><em>template loader docs</em></a>
for more.</li>
<li>Otherwise, determine the full filesystem path to the
<tt class="file docutils literal"><span class="pre">django/contrib/formtools/templates</span></tt> directory, and add that
directory to your <a class="reference internal" href="../../settings.html#std:setting-TEMPLATE_DIRS"><tt class="xref std std-setting docutils literal"><span class="pre">TEMPLATE_DIRS</span></tt></a> setting.</li>
</ul>
</li>
<li><p class="first">Create a <a class="reference internal" href="#django.contrib.formtools.preview.FormPreview" title="django.contrib.formtools.preview.FormPreview"><tt class="xref py py-class docutils literal"><span class="pre">FormPreview</span></tt></a> subclass that
overrides the <tt class="docutils literal"><span class="pre">done()</span></tt> method:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">django.contrib.formtools.preview</span> <span class="kn">import</span> <span class="n">FormPreview</span>
<span class="kn">from</span> <span class="nn">django.http</span> <span class="kn">import</span> <span class="n">HttpResponseRedirect</span>
<span class="kn">from</span> <span class="nn">myapp.models</span> <span class="kn">import</span> <span class="n">SomeModel</span>

<span class="k">class</span> <span class="nc">SomeModelFormPreview</span><span class="p">(</span><span class="n">FormPreview</span><span class="p">):</span>

    <span class="k">def</span> <span class="nf">done</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">request</span><span class="p">,</span> <span class="n">cleaned_data</span><span class="p">):</span>
        <span class="c"># Do something with the cleaned_data, then redirect</span>
        <span class="c"># to a &quot;success&quot; page.</span>
        <span class="k">return</span> <span class="n">HttpResponseRedirect</span><span class="p">(</span><span class="s">&#39;/form/success&#39;</span><span class="p">)</span>
</pre></div>
</div>
<p>This method takes an <a class="reference internal" href="../../request-response.html#django.http.HttpRequest" title="django.http.HttpRequest"><tt class="xref py py-class docutils literal"><span class="pre">HttpRequest</span></tt></a> object and a
dictionary of the form data after it has been validated and cleaned.
It should return an <a class="reference internal" href="../../request-response.html#django.http.HttpResponseRedirect" title="django.http.HttpResponseRedirect"><tt class="xref py py-class docutils literal"><span class="pre">HttpResponseRedirect</span></tt></a> that
is the end result of the form being submitted.</p>
</li>
<li><p class="first">Change your URLconf to point to an instance of your
<a class="reference internal" href="#django.contrib.formtools.preview.FormPreview" title="django.contrib.formtools.preview.FormPreview"><tt class="xref py py-class docutils literal"><span class="pre">FormPreview</span></tt></a> subclass:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">myapp.preview</span> <span class="kn">import</span> <span class="n">SomeModelFormPreview</span>
<span class="kn">from</span> <span class="nn">myapp.forms</span> <span class="kn">import</span> <span class="n">SomeModelForm</span>
<span class="kn">from</span> <span class="nn">django</span> <span class="kn">import</span> <span class="n">forms</span>
</pre></div>
</div>
<p>...and add the following line to the appropriate model in your URLconf:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="p">(</span><span class="s">r&#39;^post/$&#39;</span><span class="p">,</span> <span class="n">SomeModelFormPreview</span><span class="p">(</span><span class="n">SomeModelForm</span><span class="p">)),</span>
</pre></div>
</div>
<p>where <tt class="docutils literal"><span class="pre">SomeModelForm</span></tt> is a Form or ModelForm class for the model.</p>
</li>
<li><p class="first">Run the Django server and visit <tt class="file docutils literal"><span class="pre">/post/</span></tt> in your browser.</p>
</li>
</ol>
</div>
<div class="section" id="s-formpreview-classes">
<span id="formpreview-classes"></span><h2><tt class="docutils literal"><span class="pre">FormPreview</span></tt> classes<a class="headerlink" href="#formpreview-classes" title="Permalink to this headline">¶</a></h2>
<dl class="class">
<dt id="django.contrib.formtools.preview.FormPreview">
<em class="property">class </em><tt class="descname">FormPreview</tt><a class="reference internal" href="../../../_modules/django/contrib/formtools/preview.html#FormPreview"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.contrib.formtools.preview.FormPreview" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>

<p>A <a class="reference internal" href="#django.contrib.formtools.preview.FormPreview" title="django.contrib.formtools.preview.FormPreview"><tt class="xref py py-class docutils literal"><span class="pre">FormPreview</span></tt></a> class is a simple Python class
that represents the preview workflow.
<a class="reference internal" href="#django.contrib.formtools.preview.FormPreview" title="django.contrib.formtools.preview.FormPreview"><tt class="xref py py-class docutils literal"><span class="pre">FormPreview</span></tt></a> classes must subclass
<tt class="docutils literal"><span class="pre">django.contrib.formtools.preview.FormPreview</span></tt> and override the <tt class="docutils literal"><span class="pre">done()</span></tt>
method. They can live anywhere in your codebase.</p>
</div>
<div class="section" id="s-formpreview-templates">
<span id="formpreview-templates"></span><h2><tt class="docutils literal"><span class="pre">FormPreview</span></tt> templates<a class="headerlink" href="#formpreview-templates" title="Permalink to this headline">¶</a></h2>
<dl class="attribute">
<dt id="django.contrib.formtools.preview.FormPreview.form_template">
<tt class="descclassname">FormPreview.</tt><tt class="descname">form_template</tt><a class="headerlink" href="#django.contrib.formtools.preview.FormPreview.form_template" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>

<dl class="attribute">
<dt id="django.contrib.formtools.preview.FormPreview.preview_template">
<tt class="descclassname">FormPreview.</tt><tt class="descname">preview_template</tt><a class="headerlink" href="#django.contrib.formtools.preview.FormPreview.preview_template" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>

<p>By default, the form is rendered via the template <tt class="file docutils literal"><span class="pre">formtools/form.html</span></tt>,
and the preview page is rendered via the template <tt class="file docutils literal"><span class="pre">formtools/preview.html</span></tt>.
These values can be overridden for a particular form preview by setting
<a class="reference internal" href="#django.contrib.formtools.preview.FormPreview.preview_template" title="django.contrib.formtools.preview.FormPreview.preview_template"><tt class="xref py py-attr docutils literal"><span class="pre">preview_template</span></tt></a> and
<a class="reference internal" href="#django.contrib.formtools.preview.FormPreview.form_template" title="django.contrib.formtools.preview.FormPreview.form_template"><tt class="xref py py-attr docutils literal"><span class="pre">form_template</span></tt></a> attributes on the
FormPreview subclass. See <tt class="file docutils literal"><span class="pre">django/contrib/formtools/templates</span></tt> for the
default templates.</p>
</div>
<div class="section" id="s-advanced-formpreview-methods">
<span id="advanced-formpreview-methods"></span><h2>Advanced <tt class="docutils literal"><span class="pre">FormPreview</span></tt> methods<a class="headerlink" href="#advanced-formpreview-methods" title="Permalink to this headline">¶</a></h2>
<dl class="method">
<dt id="django.contrib.formtools.preview.FormPreview.process_preview">
<tt class="descclassname">FormPreview.</tt><tt class="descname">process_preview</tt>()<a class="reference internal" href="../../../_modules/django/contrib/formtools/preview.html#FormPreview.process_preview"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.contrib.formtools.preview.FormPreview.process_preview" title="Permalink to this definition">¶</a></dt>
<dd><p>Given a validated form, performs any extra processing before displaying the
preview page, and saves any extra data in context.</p>
<p>By default, this method is empty.  It is called after the form is validated,
but before the context is modified with hash information and rendered.</p>
</dd></dl>

</div>
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  <ul>
<li><a class="reference internal" href="#">Form preview</a><ul>
<li><a class="reference internal" href="#overview">Overview</a></li>
<li><a class="reference internal" href="#how-to-use-formpreview">How to use <tt class="docutils literal"><span class="pre">FormPreview</span></tt></a></li>
<li><a class="reference internal" href="#formpreview-classes"><tt class="docutils literal"><span class="pre">FormPreview</span></tt> classes</a></li>
<li><a class="reference internal" href="#formpreview-templates"><tt class="docutils literal"><span class="pre">FormPreview</span></tt> templates</a></li>
<li><a class="reference internal" href="#advanced-formpreview-methods">Advanced <tt class="docutils literal"><span class="pre">FormPreview</span></tt> methods</a></li>
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